package com.xigege.nio.bufferAndChannel;

import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;
import java.util.HashSet;

/**
 * Scattering： 将数据写入到buffer时，可以采用buffer数组，依次写入【分散】
 * Gathering：从buffer读取数据时，可以采用buffer数组，依次读
 */
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws Exception {
        //使用ServerSocketChannel 和 SocketChannel网络
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        //创建SocketAddress
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);

        //绑定端口到socket 并启动
        serverSocketChannel.socket().bind(inetSocketAddress);

        //创建一个buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);

        //等到客户端连接（telnet）
        SocketChannel socketChannel = serverSocketChannel.accept();
        int messageLenght = 8;

        //循环读取
        while (true) {

            int byteRead = 0;

            while (byteRead < messageLenght) {
                long l = socketChannel.read(byteBuffers);
                byteRead += l;  //累计读取的字节数
                System.out.println("byteRead=" + byteRead);
                //使用流打印 看看当前的这个buffer的position 和 limit
                Arrays.asList(byteBuffers).stream().map(buffer -> "position=" + buffer.position() + ",limit" + buffer.limit()).forEach(System.out::println);
            }
            //将所有的buffer进行flip
            Arrays.asList(byteBuffers).forEach(buffer -> buffer.flip());

            //将数据读出显示到客户端
            long byteWrite = 0;
            while (byteWrite < messageLenght) {
                long l = socketChannel.write(byteBuffers);
                byteWrite += 1;
            }

            //将所有buffer进行clear
            Arrays.asList(byteBuffers).forEach(buffer -> buffer.clear());
            System.out.println("byteRead=" + byteRead + "byteWrite=" + byteWrite + "messagelength=" + messageLenght);
        }
    }
}
